1. Field of the Invention
The present invention relates to a piezoelectric drive device that is driven by a piezoelectric element and a liquid discharging device that uses the piezoelectric drive device.
2. Description of Related Art
A diaphragm pump using a diaphragm or a tube pump using a tube can discharge liquid that contains various fillers without damaging the liquid to be conveyed when the diaphragm or tube is made of a synthetic resin. Such a pump is used in a variety of fields such as chemical, pharmaceutical, semiconductor, or printing industries because advantages that the pump does not require a sealing material and that the pump can realize a structure where the liquid does not contact metals can be obtained.
Such a pump reciprocates a plurality of pressuring rods by turns against the diaphragm or tube to apply a pressure to the diaphragm or tube or to release the pressure therefrom. In this manner, the pump repeats operations of suctioning, measuring and discharging the liquid and discharges the liquid. For the driving of the pressuring rods, an air cylinder type is known, and a cam type rotated by a motor has been also used since the cam can realize a higher-speed driving than the air cylinder (see Document: JP-A-2006-29314).
The cam-driving type can realize a faster reciprocation than the air cylinder, but the cam poses a problem that the pump becomes large because of a difficulty in configuring the cam to be compact. Especially, in a production line for a various products such as LED, the pump is mounted on an arm tip end of a production robot to discharge the liquid while moving. Although there has been a demand for a compact and lightweight pump, the cam-driving type cannot meet the demand.
As described above, a drive device that can reciprocate a driven body such as pressurizing rods at high speed and that can be configured to be compact and lightweight has been conventionally demanded as a drive source for not only the diaphragm pump or tube pump but also a variety of machines.